JP2017196800A - Ink-jet head and ink-jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet head suppressing cracks due to repetition stress of driving elements, and improving reliability of each of the driving elements: and to provide an ink-jet recording device.SOLUTION: An ink-jet head includes a substrate, a diaphragm and a driving element. The driving element includes a first electrode located on a second surface of the diaphragm, a second electrode facing the first electrode and a piezoelectric crystal disposed between the first electrode and the second electrode. The ink-jet head further includes an inter-wiring insulation film covering the second surface of the diaphragm and the driving element, and a lead-out electrode located on the inter-wiring insulation film. The inter-wiring insulation film includes a contact part exposing a part of the second electrode and connecting the second electrode and the lead-out electrode. The contact part is disposed at a position corresponding to a solid portion of a peripheral wall of a pressure chamber, on the substrate.SELECTED DRAWING: Figure 3B

Description

  Embodiments described herein relate generally to an inkjet head and an inkjet recording apparatus.

  The so-called on-demand ink jet recording method is a method in which ink droplets are ejected from nozzles in accordance with image signals to form an image with ink droplets on recording paper. The on-demand ink jet recording system includes a heating element type and a piezoelectric element type.

  In the heating element type, a heating element in the ink flow path generates bubbles in the ink. Ink droplets pushed by the bubbles are ejected from the nozzles. On the other hand, in the piezoelectric element type, the piezoelectric element (piezo element) is deformed to cause a pressure change in the ink stored in the ink chamber. Thereby, the pressurized ink droplet is ejected from the nozzle.

  An inkjet head as an example of a piezoelectric element type has a drive element (piezoelectric element, actuator) that pressurizes ink. The drive element includes, for example, a piezoelectric film and metal electrode films formed on both surfaces of the piezoelectric film.

  The ink jet head has a pressure chamber for containing ink. There is a diaphragm to which the drive element is attached at one end of the pressure chamber. There is a nozzle plate with nozzles at the other end of the pressure chamber.

  When a driving waveform (voltage) is applied to the two electrode films, an electric field in the same direction as the polarization direction is applied to the piezoelectric film through the electrode films. Thereby, the drive element expands and contracts in a direction orthogonal to the electric field direction. The diaphragm is deformed using this expansion and contraction. When the diaphragm is deformed, a pressure change occurs in the ink in the pressure chamber, and an ink droplet is ejected from the nozzle.

JP 2011-56939 A Japanese Patent No. 5724263

  In the structure of an ink jet head having a conventional configuration, a portion where a connection terminal with an external element for applying a voltage to the driving element comes in contact with the pressure chamber across the driving element. In such a configuration, a repeated stress is applied to the contact portion with the connection terminal by driving the drive element for a long period of time. Therefore, as the drive element is driven for a long period of time, there is a possibility that a crack is formed in the film forming the drive unit. Then, the current concentrates on the crack portion, which causes dielectric breakdown, and there is a possibility that the contact portion with the connection terminal becomes defective in connection. Therefore, when the portion where the connection terminal with the external element contacts is opposed to the pressure chamber across the drive element, the structure is weak against stress, and the reliability of each drive element is reduced at the contact portion with the connection terminal. It was causing.

  The present embodiment is to provide an ink jet head and an ink jet recording apparatus that can suppress cracks due to repetitive stress of a drive element and can improve the reliability of each drive element.

  An inkjet head according to one embodiment includes a base material, a diaphragm, and a drive element. The substrate has a pressure chamber for containing ink. The vibration plate has a first surface that closes the pressure chamber, and a second surface that is on the opposite side of the first surface. The driving element is on the second surface of the diaphragm, and deforms the diaphragm when a voltage is applied, thereby changing the volume of the pressure chamber and ejecting ink from the nozzle. Furthermore, the drive element includes a first electrode on the second surface of the diaphragm, a second electrode facing the first electrode, the first electrode, and the second electrode. And a piezoelectric body interposed therebetween. The wiring board further includes an inter-wiring insulating film that covers the second surface of the diaphragm and the driving element, and an extraction electrode on the inter-wiring insulating film. The inter-wiring insulating film has a contact portion that exposes a part of the second electrode and connects the second electrode and the extraction electrode. The contact portion was disposed at a position corresponding to a solid portion of the peripheral wall of the pressure chamber in the base material.

FIG. 1 is a cross-sectional view illustrating the ink jet printer according to the first embodiment. FIG. 2 is a plan view showing the main configuration of the ink jet head according to the first embodiment. 3A is a cross-sectional view taken along line IIIA-IIIA in FIG. 3B is a cross-sectional view taken along line IIIB-IIIB in FIG. 4A and 4B show a manufacturing process of the ink jet head of the first embodiment, and FIG. 4A is a cross-sectional view showing a state in which a diaphragm and an oxide film of an insulating film on a substrate are formed over the entire surface of a silicon wafer. (B) is a sectional view showing a state in which a lower electrode, a piezoelectric film, and an upper electrode are sequentially laminated on the diaphragm and the insulating film on the substrate, and (C) is a state in which the lower electrode, the piezoelectric film, and the upper electrode are patterned. FIG. 5A is a cross-sectional view showing a state in which an inter-wiring insulating film is formed on the vibration plate, the insulating film on the substrate, and the driving element, and FIG. 5B is a cross-sectional view showing a state in which the inter-wiring insulating film is patterned. FIG. 3C is a cross-sectional view showing a state in which the extraction electrode is formed. FIG. 6A is a cross-sectional view showing a state in which a protective film is formed on the diaphragm, the insulating film on the substrate, the inter-wiring insulating film, and the extraction electrode, and FIG. 6B shows a nozzle formed by patterning the protective film. FIG. 6C is a cross-sectional view showing a state in which an ink-repellent film is formed on the protective film. FIG. 7 is a cross-sectional view showing a part of the ink jet head of the first embodiment. FIG. 8 is a longitudinal sectional view showing a part of the inkjet head according to the second embodiment.

  The first embodiment will be described below with reference to FIGS. 1 to 7. Note that one or more examples of other expressions may be attached to each element capable of a plurality of expressions. However, this does not deny that a different expression is given for an element to which no other expression is attached, and does not restrict other expressions not illustrated. Each drawing schematically shows an embodiment, and the size of each element shown in the drawing may differ from the explanation of the embodiment.

  FIG. 1 is a cross-sectional view showing an ink jet printer 1 according to the first embodiment. The ink jet printer 1 is an example of an ink jet recording apparatus. The ink jet recording apparatus is not limited to this, and may be another apparatus such as a copying machine.

  As shown in FIG. 1, the inkjet printer 1 performs various processes such as image formation while conveying a recording paper P that is a recording medium, for example. The ink jet printer 1 includes a housing 10, a paper feed cassette 11, a paper discharge tray 12, a holding roller (drum) 13, a conveying device 14, a holding device 15, an image forming device 16, and a static elimination device 17. And a reversing device 18 and a cleaning device 19.

  The paper feed cassette 11 accommodates a plurality of recording papers P and is disposed in the housing 10. The paper discharge tray 12 is at the top of the housing 10. The recording paper P on which an image is formed by the ink jet printer 1 is discharged to the paper discharge tray 12.

  The transport device 14 has a plurality of guides and a plurality of transport rollers arranged along a path along which the recording paper P is transported. The conveyance roller is driven and rotated by a motor to convey the recording paper P from the paper feed cassette 11 to the paper discharge tray 12.

  The holding roller 13 has a cylindrical frame formed of a conductor and a thin insulating layer formed on the surface of the frame. The frame is grounded (ground connection). The holding roller 13 conveys the recording paper P by rotating while holding the recording paper P on the surface thereof.

  The holding device 15 holds the recording paper P carried out of the paper feed cassette 11 by the transport device 14 by adsorbing it on the surface (outer peripheral surface) of the holding roller 13. The holding device 15 presses the recording paper P against the holding roller 13 and then attracts the recording paper P to the holding roller 13 by electrostatic force due to charging.

  The image forming apparatus 16 forms an image on the recording paper P held on the outer surface of the holding roller 13 by the holding device 15. The image forming apparatus 16 includes a plurality of inkjet heads 21 that face the surface of the holding roller 13. The plurality of inkjet heads 21 form images by ejecting, for example, four colors of ink of cyan, magenta, yellow, and black onto the recording paper P, respectively.

  The neutralization peeling device 17 peels the recording paper P on which the image is formed from the holding roller 13 by neutralizing the recording paper P. The neutralization peeling device 17 supplies electric charges to neutralize the recording paper P, and inserts a claw between the recording paper P and the holding roller 13. As a result, the recording paper P is peeled off from the holding roller 13. The recording paper P peeled off from the holding roller 13 is transported by the transport device 14 to the paper discharge tray 12 or the reversing device 18.

  The cleaning device 19 cleans the holding roller 13. The cleaning device 19 is downstream of the static elimination device 17 in the rotation direction of the holding roller 13. The cleaning device 19 brings the cleaning member 19 a into contact with the surface of the rotating holding roller 13 and cleans the surface of the rotating holding roller 13.

  The reversing device 18 reverses the front and back surfaces of the recording paper P peeled from the holding roller 13 and supplies the recording paper P onto the front surface of the holding roller 13 again. The reversing device 18 reverses the recording paper P by, for example, conveying the recording paper P along a predetermined reversing path for switching back the recording paper P in the front-rear direction.

  FIG. 2 is a plan view showing the main configuration of the inkjet head 21. 3A is a cross-sectional view showing a part of the inkjet head 21 cut along the line IIIA-IIIA in FIG. 2, and FIG. 3B shows a part of the inkjet head 21 cut along the line IIIB-IIIB in FIG. It is sectional drawing shown. For the sake of explanation, FIG. 2 shows various elements that are originally hidden by solid lines.

  The ink jet printer 1 includes a plurality of ink tanks (not shown) connected to a plurality of ink jet heads 21 and a plurality of control units (not shown). The inkjet head 21 is connected to an ink tank that stores ink of a corresponding color.

  The inkjet head 21 forms characters and images by ejecting ink droplets onto the recording paper P held by the holding roller 13. The inkjet head 21 includes a nozzle plate 100, a pressure chamber structure 120, and an ink flow path structure 400. The pressure chamber structure 120 is an example of a base material.

  The nozzle plate 100 is formed in a rectangular plate shape. The nozzle plate 100 is formed as an integral structure on the pressure chamber structure 120. The nozzle plate 100 includes a plurality of nozzles (orifices and ink ejection holes) 109 and a plurality of driving elements (piezoelectric elements and actuators) 113. The drive element 113 includes a lower electrode (first electrode) 103, a piezoelectric film (piezoelectric body) 104, and an upper electrode (second electrode) 105.

  The plurality of nozzles 109 are circular holes. The diameter of the nozzle 109 is, for example, 20 μm. The nozzles 109 are arranged in a plurality of rows on the nozzle plate 100, and a plurality of drive elements 113 are arranged at high density.

  The pressure chamber structure 120 is formed in a rectangular plate shape using a silicon wafer. The pressure chamber structure 120 is not limited to this, and may be another semiconductor such as silicon carbide (SiC) or a germanium substrate. The substrate is not limited to this, and may be formed of other materials such as ceramics, glass, quartz, resin, or metal. The ceramics used are, for example, alumina ceramics, zirconia, silicon carbide, silicon nitride or nitrides, carbides or oxides such as barium titanate. The resin used is, for example, a plastic material such as ABS (acrylonitrile butadiene styrene), polyacetal, polyamide, polycarbonate, or polyethersulfone. The metal used is, for example, aluminum or titanium. The thickness of the pressure chamber structure 120 is, for example, 725 μm. The thickness of the pressure chamber structure 120 is, for example, in the range of 100 to 775 μm.

  The pressure chamber structure 120 has a plurality of pressure chambers (ink chambers) 121. As shown in FIG. 2, the pressure chamber 121 is a circular hole. The diameter of the pressure chamber 121 is 190 μm, for example. The shape of the pressure chamber 121 is not limited to this. The pressure chamber 121 penetrates the pressure chamber structure 120 in the thickness direction.

  The plurality of pressure chambers 121 are arranged corresponding to the plurality of nozzles 109. For this reason, the corresponding nozzle 109 communicates with the pressure chamber 121. The pressure chamber 121 is connected to the outside of the inkjet head 21 via the nozzle 109.

  The ink flow path structure 400 is formed in a rectangular plate shape using, for example, stainless steel. The material of the ink flow path structure 400 is not limited to stainless steel. For example, you may form with other materials like ceramics or resin. The ceramics used are, for example, alumina ceramics, zirconia, silicon carbide, nitrides such as silicon nitride, carbides or oxides. The resin used is, for example, a plastic material such as ABS, polyacetal, polyamide, polycarbonate, or polyethersulfone. The material of the ink flow path structure 400 is selected in consideration of the difference in expansion coefficient with the nozzle plate 100 so as not to affect the generation of pressure for ejecting ink.

  The ink flow path structure 400 is bonded to the pressure chamber structure 120 by, for example, an epoxy adhesive. The ink flow path structure 400 includes an ink flow path 401, an ink supply port (not shown), and an ink discharge port.

  The ink flow path 401 is a groove formed on the surface of the ink flow path structure 400. The ink supply port opens at one end of the ink flow path. The ink supply port is connected to the ink tank via a tube, for example. The ink tank is connected to the plurality of pressure chambers 121 via the ink flow path 401.

  The ink in the ink tank flows into the ink flow path 401 through the ink supply port. The ink supplied to the ink flow path 401 is supplied to the plurality of pressure chambers 121. The ink filled in the pressure chamber 121 also flows into the nozzle 109 that opens in the pressure chamber 121. The ink jet printer 1 keeps the ink in the nozzle 109 by keeping the ink pressure at an appropriate negative pressure. The ink causes a meniscus in the nozzle 109 and is maintained so as not to leak from the nozzle 109.

  Next, the nozzle plate 100 will be described in detail. As shown in FIGS. 2 and 3A, 3B, the nozzle plate 100 includes the nozzle 109 and the vibration plate 101, the substrate insulating film 102, the lower electrode 103, the piezoelectric film 104, the upper electrode 105, and the wiring. The insulating film 106, the protective film 110, and the ink repellent film 111 are included. The inter-wiring insulating film 106 and the protective film 110 are examples of insulating portions.

The vibration plate 101 and the on-substrate insulating film 102 are formed in a rectangular plate shape by, for example, SiO ₂ (silicon dioxide) formed on the pressure chamber structure 120. In other words, the vibration plate 101 and the on-substrate insulating film 102 are oxide films of the pressure chamber structure 120 that is a silicon wafer. The vibration plate 101 and the insulating film 102 on the substrate are made of single crystal Si (silicon), Al ₂ O ₃ (aluminum oxide), HfO ₂ (hafnium oxide), ZrO ₂ (zirconium oxide), or DLC (Diamond Like Carbon). It may be formed of other materials. The thickness of the vibration plate 101 and the on-substrate insulating film 102 is, for example, 4 μm. The thickness of the vibration plate 101 and the on-substrate insulating film 102 is generally in the range of 1 to 50 μm. The diaphragm 101 and the on-substrate insulating film 102 are made of the same film, and the names are distinguished according to the existence area. In other words, the region in contact with the pressure chamber 121 is the diaphragm 101, and the region in contact with the pressure chamber structure 120 is the insulating film 102 on the substrate.

  The diaphragm 101 has a first surface 101a and a second surface 101b. The first surface 101a closes the plurality of pressure chambers 121. The second surface 101b is located on the opposite side of the first surface 101a.

  The on-substrate insulating film 102 has a first surface 102a and a second surface 102b. The first surface 102 a is fixed to the pressure chamber structure 120. The second surface 102b is located on the opposite side of the first surface 102a.

  The lower electrode 103 is formed on the second surface 101 b of the diaphragm 101 and the second surface 102 b of the on-substrate insulating film 102. The lower electrode 103 is, for example, a thin film of Pt (platinum) and Al (aluminum).

  The upper electrode 105 is formed so that the piezoelectric film 104 is sandwiched between a part of the lower electrode 103 and the upper electrode 105. The upper electrode 105 is, for example, a thin film of Ti (titanium) and Pt. The lower electrode 103 and the upper electrode 105 are Ni (nickel), Cu (copper), Al (aluminum), Ag (silver), Ti (titanium), W (tungsten), Mo (molybdenum), Au (gold). It may be formed of other materials such as

  The thickness of the lower electrode 103 and the upper electrode 105 is, for example, 0.5 μm. The film thicknesses of the lower electrode 103 and the upper electrode 105 are generally in the range of 0.01 to 1 μm.

  As shown in FIGS. 2, 3 </ b> A, and 3 </ b> B, the driving element 113 is formed of a laminated body in which a lower electrode 103 portion, a piezoelectric film 104, and an upper electrode 105 portion are sequentially laminated. The piezoelectric film 104 is interposed between the lower electrode 103 portion and the upper electrode 105 portion. The upper electrode 105 is in contact with the inter-wiring insulating film 106. The driving element 113 generates a pressure for ejecting ink droplets from the corresponding nozzle 109 in the ink in the corresponding pressure chamber 121.

  An electrode portion 103 a in contact with the piezoelectric film 104 in the lower electrode 103 is on the second surface 101 b of the diaphragm 101. The electrode portion 103 a of the lower electrode 103 is formed in an annular shape surrounding the nozzle 109 and is located on the same axis as the nozzle 109. Furthermore, the outer diameter of the electrode portion 103a of the lower electrode 103 is, for example, 133 μm. The inner diameter of the electrode portion 103a of the lower electrode 103 is, for example, 30 μm.

  Further, as shown in FIG. 2, a part of the electrode portion 103 a of the lower electrode 103 is linearly extended laterally from the annular portion (electrode portion 103 a), and the individual electrode portion is formed on the insulating film 102 on the substrate. A linear extending portion 103b is formed. As shown in FIG. 3B, the extending portion 103 b extends from above the vibration plate 101 to the substrate insulating film 102 side and is also formed on the substrate insulating film 102.

  As shown in FIGS. 2, 3 </ b> A, and 3 </ b> B, the piezoelectric film 104 surrounds the nozzle 109 and is formed in an annular shape that is approximately the same size as the electrode portion 103 a of the lower electrode 103. The piezoelectric film 104 is formed slightly smaller than the electrode portion 103 a of the lower electrode 103, but may be larger than the electrode portion 103 a of the lower electrode 103. The piezoelectric film 104 is located on the same axis as the nozzle 109. The piezoelectric film 104 covers the electrode portion 103 a of the lower electrode 103. Furthermore, a part of the piezoelectric film 104 is extended from an annular portion and is also disposed on the extended portion 103 b of the lower electrode 103 formed on the insulating film 102 on the substrate.

The piezoelectric film 104 is a film of lead zirconate titanate (PZT) which is a piezoelectric material. The piezoelectric film 104 is not limited to this, for example, PTO (PbTiO _3: lead _{titanate), PMNT (Pb (Mg 1/3} Nb 2/3) O 3 -PbTiO 3), PZNT (Pb (Zn 1 / ₃ Nb _2/3 ) O ₃ —PbTiO ₃ ), ZnO, and AlN may be used to form the piezoelectric material.

  The thickness of the piezoelectric film 104 is 2 μm, for example. The thickness of the piezoelectric film 104 is determined by, for example, piezoelectric characteristics and dielectric breakdown voltage. The thickness of the piezoelectric film 104 is generally in the range of 0.1 μm to 5 μm.

  The piezoelectric film 104 generates polarization in the thickness direction. When an electric field in the same direction as the polarization direction is applied to the piezoelectric film 104, the piezoelectric film 104 expands and contracts in a direction orthogonal to the direction of the electric field. In other words, the piezoelectric film 104 contracts or expands in a direction (in-plane direction) orthogonal to the film thickness.

  When a ferroelectric material such as PZT is used as the piezoelectric film 104, polarization inversion occurs by applying an electric field opposite to the polarization direction. Therefore, it is possible to apply an electric field substantially only in the same direction as the polarization direction, and by applying the electric field, the piezoelectric film 104 extends in the film thickness direction and is perpendicular to the film thickness (in-plane direction). ).

  The upper electrode 105 surrounds the nozzle 109 and has an electrode portion 105 a formed in an annular shape having approximately the same size as the electrode portion 103 a of the lower electrode 103 and the piezoelectric film 104. The upper electrode 105 is formed slightly smaller than the piezoelectric film 104, but may be larger than the piezoelectric film 104. The electrode part 105 a is located on the same axis as the nozzle 109. A part of the electrode portion 105 a of the upper electrode 105 is linearly extended laterally from an annular portion (electrode portion 105 a), and a linear extended portion 105 b is formed on the insulating film 102 on the substrate. . The extending portion 105 b extends from the vibration plate 101 to the substrate insulating film 102 side and is also formed on the substrate insulating film 102. The upper electrode 105 covers the piezoelectric film 104. In other words, the upper electrode 105 is provided on the discharge side of the piezoelectric film 104 (side facing the ink jet head 21).

  The piezoelectric film 104 is interposed between the electrode portion 103 a of the lower electrode 103 and the electrode portion 105 a of the upper electrode 105, and between the extended portion 103 b of the lower electrode 103 and the extended portion 105 b of the upper electrode 105. In other words, the electrode portion 103a of the lower electrode 103 and the electrode portion 105a of the upper electrode 105, the extending portion 103b of the lower electrode 103, and the extending portion 105b of the upper electrode 105 overlap the piezoelectric film 104. The upper electrode 105 faces the electrode portion 103 a and the extending portion 103 b of the lower electrode 103 with the piezoelectric film 104 interposed therebetween.

  The inter-wiring insulating film 106 covers the second surface 101 b of the vibration plate 101, the surface of the driving element 113, and the electrode portion of the lower electrode 103 that is not in contact with the piezoelectric film 104. The inter-wiring insulating film 106 has a plurality of holes that expose the connection portions of the lower electrode 103 with the external terminals.

The inter-wiring insulating film 106 is made of, for example, SiO ₂ . The inter-wiring insulating film 106 may be formed of other materials such as SiN (silicon nitride), for example. The inter-wiring insulating film 106 has a substantially uniform thickness on the second surface 101 b of the vibration plate 101, the surface of the driving element 113, and the extending portion 103 b of the lower electrode 103. The thickness of the inter-wiring insulating film 106 is 1 μm. The thickness of the inter-wiring insulating film 106 is approximately in the range of 0.1 μm to 5 μm. Note that the thickness of the inter-wiring insulating film 106 may be partially different.

  The inter-wiring insulating film 106 has a plurality of contact holes (contact portions) 107. As shown in FIG. 3B, the contact hole 107 is disposed at a position corresponding to the solid portion of the peripheral wall of the pressure chamber 121 in the pressure chamber structure 120. Here, the contact hole 107 is a hole for exposing a part of the upper electrode 105 provided on the region of the corresponding driving element 113 where the on-substrate insulating film 102 exists. The contact hole 107 is formed in a circular shape with a diameter of 20 μm, for example.

  As shown in FIGS. 2 and 3B, the upper electrode 105 is connected to the extraction electrode 108 through the contact hole 107. The extraction electrode 108 is provided on the inter-wiring insulating film 106 and prevents electrical connection with the lower electrode 103.

  The protective film 110 is on the second surface 101 b of the diaphragm 101. The protective film 110 is made of, for example, photosensitive polyimide such as Photo Nice (registered trademark) manufactured by Toray Industries, Inc. In other words, the protective film 110 is formed of an insulating material that is different from the inter-wiring insulating film 106. The protective film 110 is not limited to this, and may be formed of other insulating materials such as resin or ceramics. Resins used are plastic materials such as other types of polyimide, ABS, polyacetal, polyamide, polycarbonate, and polyethersulfone. The ceramics used are, for example, nitrides such as zirconia, silicon carbide, silicon nitride, barium titanate, or oxides. Further, the protective film 110 may be formed of a metal material as long as it has an insulating property with respect to the driving element and the upper electrode 105. The metal material is, for example, aluminum, SUS, or titanium.

  The material of the protective film 110 is selected in consideration of heat resistance, insulation, thermal expansion coefficient, smoothness, and ink wettability. When the ink jet printer 1 uses ink having high conductivity, the insulating property of the material can affect the degree of ink deterioration when the drive element 113 is driven.

  The protective film 110 covers the second surface 101 b of the vibration plate 101, the surface of the inter-wiring insulating film 106, and a part of the extraction electrode 108. In other words, the protective film 110 covers a part of the drive element 113 and the lower electrode 103 from above the inter-wiring insulating film 106. The protective film 110 protects the driving element 113, the lower electrode 103, and the upper electrode 105 from, for example, ink or moisture in the air. The protective film 110 has a plurality of holes that expose connection portions of the lower electrode 103 and the upper electrode 105 to a plurality of external terminals, respectively.

The material of the protective film 110 is different from the material of the diaphragm 101 in Young's modulus. The Young's modulus of SiO ₂ forming the vibration plate 101 is 80.6 GPa. On the other hand, the Young's modulus of the polyimide forming the protective film 110 is 4 GPa. That is, the Young's modulus of the protective film 110 is smaller than the Young's modulus of the diaphragm 101.

  The surface of the protective film 110 is formed to be roughly smooth, but has minute irregularities. For example, in the portion where the driving element 113 is provided, the surface of the protective film 110 is raised as compared with other portions. The surface of the protective film 110 is located on the opposite side of the surface fixed to the vibration plate 101.

  The thickness of the protective film 110 other than the portion where the driving element 113, the lower electrode 103, and the extraction electrode 108 are present is about 4 μm. The thickness of the protective film 110 is generally in the range of 1 to 50 μm. The thickness of the protective film 110 is the distance from the second surface 101 b of the diaphragm 101 to the surface of the protective film 110. The thickness of the protective film 110 formed on the driving element 113 is about 2.5 μm. The thickness of the protective film 110 is a distance from the surface of the inter-wiring insulating film 106 on the driving element 113 to the surface of the protective film 110.

  The ink repellent film 111 covers the protective film 110 and a part of the inter-wiring insulating film 106. The ink repellent film 111 is formed of, for example, a fluorine-containing organic material or a silicone-based liquid repellent material having liquid repellency, such as Cytop (registered trademark) of Asahi Glass Co., Ltd. The ink repellent film 111 may be formed of other materials.

  The ink repellent film 111 exposes the external connection terminal portion of the lower electrode 103 and the external connection terminal portion of the upper electrode 105, and exposes the protective film 110 without covering the periphery thereof. The surface of the ink repellent film 111 forms the surface of the nozzle plate 100. The surface of the ink repellent film 111 is located on the opposite side of the surface fixed to the protective film 110.

  The thickness of the ink repellent film 111 is, for example, 1 μm. The thickness of the ink repellent film 111 is, for example, in the range of 0.01 to 10 μm. The thickness of the ink repellent film 111 in the portion where the driving element 113 is provided, that is, the portion where the upper electrode 105 and the lower electrode 103 are present is thinner than the other portions. The thickness of the ink repellent film 111 may be constant.

  If ink droplets ejected from the nozzle 109 adhere to the vicinity of the nozzle 109, the stability of ink ejection may be reduced. The ink repellent film 111 suppresses ink droplets from adhering to the surface of the nozzle plate 100.

  The nozzle 109 passes through the vibration plate 101, the protective film 110, and the ink repellent film 111. In other words, the nozzle 109 is formed on the vibration plate 101, the protective film 110, and the ink repellent film 111. Since the vibration plate 101 and the protective film 110 have ink affinity (lyophilic property), the meniscus of the ink stored in the pressure chamber 121 is kept in the nozzle 109. A part of the protective film 110 is interposed between the nozzle 109 and the inner peripheral surface of the drive element 113.

  A control unit (not shown) is connected to the external connection terminal portion of the lower electrode 103 via, for example, a flexible cable. The control unit is, for example, an IC that controls the inkjet head 21 or a microcomputer that controls the inkjet printer 1. On the other hand, the external connection terminal portion of the upper electrode 105 is connected to, for example, GND (ground ground = 0V).

  The control unit causes the lower electrode 103 to transmit a signal for driving the corresponding drive element 113. The lower electrode 103 is used as an individual electrode for operating a plurality of driving elements 113 independently.

  The inkjet head 21 performs printing (image formation) as follows, for example. A print instruction signal is input to the control unit by a user operation. The control unit applies signals to the plurality of drive elements 113 based on the print instruction. In other words, the control unit applies a driving voltage to the electrode portion of the lower electrode 103 that is in contact with the piezoelectric film 104.

  When a signal is applied to the electrode portion 103 a of the lower electrode 103, a potential difference is generated between the electrode portion 103 a of the lower electrode 103 and the upper electrode 105. As a result, an electric field in the same direction as the polarization direction is applied to the piezoelectric film 104, and the drive element 113 expands and contracts in a direction orthogonal to the electric field direction.

  In such a nozzle plate 100, when the drive element 113 extends in a direction orthogonal to the electric field direction, the vibration plate 101 is curved so as to reduce the volume of the pressure chamber 121. On the other hand, when the driving element 113 is contracted in a direction orthogonal to the electric field direction, the diaphragm 101 is curved so as to increase the volume of the pressure chamber 121. At this time, the inter-wiring insulating film 106 and the protective film 110 inhibit the bending.

  More specifically, as shown in FIGS. 3A and 3B, the driving element 113 is sandwiched between the vibration plate 101, the inter-wiring insulating film 106, and the protective film 110. For this reason, when the drive element 113 extends in a direction orthogonal to the electric field direction, the diaphragm 101 is subjected to a force that deforms into a concave shape with respect to the pressure chamber 121 side. In other words, the diaphragm 101 tends to bend in a direction that increases the volume of the pressure chamber 121. On the contrary, the inter-wiring insulating film 106 and the protective film 110 are subjected to a force that deforms into a convex shape with respect to the pressure chamber 121 side. In other words, the inter-wiring insulating film 106 and the protective film 110 tend to bend in a direction that reduces the volume of the pressure chamber 121.

  On the other hand, when the driving element 113 is contracted in a direction orthogonal to the electric field direction, the diaphragm 101 is subjected to a force that deforms into a convex shape with respect to the pressure chamber 121 side. In other words, the diaphragm 101 tends to bend in a direction that reduces the volume of the pressure chamber 121. Further, the inter-wiring insulating film 106 and the protective film 110 are subjected to a force that deforms into a concave shape with respect to the pressure chamber 121 side. In other words, the inter-wiring insulating film 106 and the protective film 110 tend to bend in a direction that increases the volume of the pressure chamber 121.

  As described above, the vibration plate 101, the inter-wiring insulating film 106, and the protective film 110 tend to bend in opposite directions. That is, the insulating portion formed by the inter-wiring insulating film 106 and the protective film 110 generates a force (film stress) that inhibits the deformation of the vibration plate 101 by the driving element 113.

The amount of deformation of the constituent member of the drive element 113 is affected by the Young's modulus and the thickness of the member. The polyimide forming the protective film 110 has a Young's modulus smaller than that of SiO ₂ forming the vibration plate 101. For this reason, the protective film 110 has a larger deformation amount with respect to the same force than the diaphragm 101. Further, the inter-wiring insulating film 106 is thinner than the vibration plate 101. For this reason, the inter-wiring insulating film 106 has a larger deformation amount with respect to the same force than the vibration plate 101.

  As described above, the drive element 113 operates in the bending mode (bending vibration). The drive element 113 changes the volume of the pressure chamber 121 by deforming the diaphragm 101 when a voltage is applied.

  First, the drive element 113 increases the volume of the pressure chamber 121 by deforming the diaphragm 101 into a concave shape with respect to the pressure chamber 121 side. As a result, a negative pressure is generated in the ink stored in the pressure chamber 121, and the ink flows into the pressure chamber 121.

  Next, the drive element 113 reduces the volume of the pressure chamber 121 by deforming the diaphragm 101 into a convex shape with respect to the pressure chamber 121 side. Thereby, the ink in the pressure chamber 121 is pressurized. Thereby, the pressurized ink is ejected from the nozzle 109.

  The greater the difference in Young's modulus between the vibration plate 101 and the protective film 110, the lower the voltage at which ink can be ejected, and the ink jet head 21 can eject ink efficiently. Furthermore, the greater the difference in thickness between the insulating portion formed by the inter-wiring insulating film 106 and the protective film 110 and the vibration plate 101, the lower the voltage at which ink can be ejected, and the ink-jet head 21 can efficiently perform ink ejection. Can be discharged.

Next, an example of a method for manufacturing the inkjet head 21 will be described with reference to FIGS. First, as shown in FIG. 4A, the SiO ₂ film 120a as the diaphragm 101 and the insulating film 102 on the substrate is formed on the entire surface of the pressure chamber structure 120 (silicon wafer) before the pressure chamber 121 is formed. Is deposited. The SiO ₂ film 120a is formed by a thermal oxide film method, for example. The SiO ₂ film 120a may be formed by other methods such as a CVD method.

  The silicon wafer forming the pressure chamber structure 120 is a single large disk. A plurality of pressure chamber structures 120 are later cut from the silicon wafer. However, the present invention is not limited to this, and one pressure chamber structure 120 may be formed from one rectangular silicon wafer.

  The silicon wafer is repeatedly heated and a thin film is formed in the manufacturing process of the inkjet head 21. For this reason, the silicon wafer has heat resistance, conforms to SEMI (Semiconductor Equipment and Materials International) standard, and is smoothed by mirror polishing.

Next, as shown in FIG. 4B, a metal film for forming the lower electrode 103 is formed on the SiO ₂ film 120a. First, a Ti film and a Pt film are sequentially formed by sputtering. The film thickness of Pt is, for example, 0.45 μm, and the film thickness of Ti is, for example, 0.05 μm. The metal film may be formed by other manufacturing methods such as vapor deposition and plating.

  Next, the piezoelectric film 104 is formed on the metal film that forms the lower electrode 103. The piezoelectric film 104 is formed by, for example, an RF magnetron sputtering method. At this time, the temperature of the silicon wafer is set to 350 ° C., for example. After the film formation, the piezoelectric film 104 is heat-treated at 650 ° C. for 3 hours in order to impart piezoelectricity to the piezoelectric film 104. Thereby, the piezoelectric film 104 obtains good crystallinity and good piezoelectric performance. The piezoelectric film 104 may be formed by other manufacturing methods such as a CVD (chemical vapor deposition method), a sol-gel method, an AD method (aerosol deposition method), and a hydrothermal synthesis method.

  Next, a Pt metal film for forming the upper electrode 105 is formed on the piezoelectric film 104. The metal film is formed by, for example, a sputtering method. The metal film may be formed by other manufacturing methods such as vacuum deposition and plating.

  Next, by etching the metal film and the piezoelectric film 104 of the upper electrode 105, the upper electrode 105 and the piezoelectric film 104 are patterned as shown in FIG. The patterning is performed by creating an etching mask on the metal film of the upper electrode 105 and removing the metal film and the piezoelectric film 104 other than the etching mask by etching. The metal film and the piezoelectric film 104 are patterned simultaneously (together). The metal film and the piezoelectric film 104 may be individually patterned. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

  Next, the lower electrode 103 is formed by patterning. For patterning, an etching mask is formed on the piezoelectric film 104 and the upper electrode 105 and the metal film (Pt / Ti) of the lower electrode 103 below the piezoelectric film 104, and the metal film other than the etching mask is etched. Do by removing. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

A nozzle 109 is formed at the center of the annular portion of the lower electrode 103 and the upper electrode 105 and the piezoelectric film 104. At this time, a portion that is concentric with the center of the electrode portion 103a of the lower electrode 103, the electrode portion 105a of the upper electrode 105, and the annular portion of the piezoelectric film 104 is formed without the metal film and the piezoelectric film 104 and SiO ₂ An extended portion 103b of the lower electrode 103 and an extended portion 105b of the upper electrode 105 are formed on the film 120a. Thus, the drive element 113 is formed on the SiO ₂ film 120a. By the patterning, the SiO ₂ film 120a (the vibration plate 101 and the insulating film 102 on the substrate) is exposed except for the external connection terminal portion of the lower electrode 103, the upper electrode 105, and the driving element 113.

Next, as illustrated in FIG. 5A, the inter-wiring insulating film 106 is formed on the SiO ₂ film 120 a and the driving element 113. The inter-wiring insulating film 106 is formed by a CVD method that can realize good insulating properties at low temperature. The inter-wiring insulating film 106 is not limited to this, and may be formed by other methods such as sputtering or vapor deposition.

  The inter-wiring insulating film 106 is patterned after film formation as shown in FIG. Thereby, in order to form the nozzle 109, a portion 106 a that does not have the inter-wiring insulating film 106 that is concentric with the center of the driving element 113 is formed. At the same time, a contact hole 107 is formed. The diameter of the portion 106a without the inter-wiring insulating film 106 is, for example, 10 μm. The patterning is performed by removing the inter-wiring insulating film 106 other than the etching mask by etching. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, fixing, and post-baking.

  Next, as shown in FIG. 5C, a metal film for forming the extraction electrode 108 is formed on the inter-wiring insulating film 106. The metal film is, for example, a Ti (titanium) / Al (aluminum) thin film formed by a sputtering method. The film thickness of Ti is, for example, 0.1 μm, and the film thickness of Al is, for example, 0.4 μm. The metal film may be formed by other manufacturing methods such as vacuum deposition and plating. The metal film is connected to either the lower electrode 103 or the upper electrode 105 through the contact hole 107.

  By patterning the metal film, an external connection terminal portion of the lower electrode 103 and an external connection terminal portion of the upper electrode 105 are formed. The patterning is performed by creating an etching mask on the metal film and removing the metal film other than the etching mask by etching. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

Next, the SiO ₂ film 120 a for forming the vibration plate 101 is patterned to form a part of the nozzle 109. Patterning is made an etching mask on the SiO ₂ film 120a, performs SiO ₂ film 120a other than the etching mask by removing by etching. The etching mask is formed by application of a photosensitive resist on the vibration plate 101, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

Next, as shown in FIG. 6A, a protective film 110 is formed on the SiO ₂ film 120a, the inter-wiring insulating film 106, and the extraction electrode 108 by spin coating (spin coating). That is, the protective film 110 that covers the inter-wiring insulating film 106 is formed. First, the SiO ₂ film 120a and the inter-wiring insulating film 106 are covered with a solution containing a polyimide precursor. Next, the silicon wafer is rotated to smooth the solution surface. The protective film 110 is formed by performing thermal polymerization and solvent removal by baking.

  The method for forming the protective film 110 is not limited to the spin coating method. The protective film 110 may be formed by other methods such as CVD, vacuum deposition, or plating.

  By patterning the protective film 110 as shown in FIG. 6B, the nozzle 109 is formed, and the external connection terminal portion of the lower electrode 103 and the external connection terminal portion of the upper electrode 105 are exposed. The patterning is performed according to a procedure corresponding to the material of the protective film 110.

  As an example, the case where the protective film 110 is formed of non-photosensitive polyimide such as Semicofine (registered trademark) of Toray Industries, Inc. will be described. First, a solution containing a polyimide precursor is formed on the inter-wiring insulating film 106 by a spin coating method, and is subjected to thermal polymerization and solvent removal by baking to be baked. Thereafter, an etching mask is formed on the non-photosensitive polyimide film, and the polyimide film other than the etching mask is removed by etching to perform patterning. The etching mask is formed by application of a photosensitive resist on the non-photosensitive polyimide film, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

  As another example, the case where the protective film 110 is formed of photosensitive polyimide such as Photo Nice (registered trademark) of Toray Industries, Inc. will be described. First, after a solution is formed on the inter-wiring insulating film 106 by a spin coating method, pre-baking is performed. Thereafter, patterning is performed through exposure using a mask and a development process. In the case of positive photosensitive polyimide, the mask has openings corresponding to the nozzle 109, the external connection terminal portion of the lower electrode 103, and the external connection terminal portion of the upper electrode 105 (light is transmitted). In the case of negative photosensitive polyimide, the mask shields light from portions corresponding to the nozzle 109, the external connection terminal portion of the lower electrode 103, and the external connection terminal portion of the upper electrode 105. Thereafter, post-baking is performed, and the protective film 110 is fired.

  Next, as shown in FIG. 6C, an ink repellent film 111 is formed over the protective film 110. The ink repellent film 111 is formed by spin coating a liquid ink repellent film material on the protective film 110.

  Next, the film forming the ink repellent film 111 is patterned. The patterning is performed by creating an etching mask on the ink repellent film 111 and removing the ink repellent film 111 other than the etching mask by etching. The etching mask is formed by applying a photosensitive resist on the ink-repellent film 111, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

Next, a cover tape is stuck on the ink repellent film 111. The cover tape is, for example, a back surface protective tape for chemical mechanical polishing (CMP) of a silicon wafer. The pressure chamber structure 120 with the cover tape attached is turned upside down to form a plurality of pressure chambers 121 in the pressure chamber structure 120 as shown in FIG. The pressure chamber 121 is formed by patterning. By forming the pressure chamber 121, the region in contact with the pressure chamber 121 in the SiO ₂ film 120 a becomes the vibration plate 101 and the region in contact with the pressure chamber structure 120 becomes the insulating film 102 on the substrate.

  3A and 3B are cross-sectional views showing the inkjet head 21 on which the insulating protective film 110 according to the first embodiment is formed. A vertical deep dry etching called Deep-RIE dedicated to a silicon substrate (for example, see International Publication No. 2003/030239) is performed to etch the pressure chamber structure 120 to form the pressure chamber 121. At this time, a resist mask in which a desired pattern is formed on the back surface of the pressure chamber structure 120, which is a silicon wafer, is formed, whereby the pressure chamber 121 is formed in the desired pattern. The resist mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

The SF6 gas used for the etching does not exert an etching action on the SiO _{2 of the} vibration plate 101 and the polyimide of the protective film 110. Therefore, the progress of dry etching of the silicon wafer forming the pressure chamber 121 stops at the SiO ₂ film 120 a of the vibration plate 101. In other words, the SiO ₂ film 120a of the vibration plate 101 functions as a stop layer for the etching.

  Note that for the above-described etching, various methods such as a wet etching method using a chemical solution and a dry etching method using plasma may be used. Further, the etching method and etching conditions may be changed depending on the material.

As described above, from the process of forming the drive element 113 and the nozzle 109 on the vibration plate 101 of the SiO ₂ film 120a to the process of forming the pressure chamber 121 in the pressure chamber structure 120, the film forming technique, photolithography etching is performed. Technology, and by spin coating. For this reason, the nozzle 109, the drive element 113, and the pressure chamber 121 are precisely and easily formed on one silicon wafer.

  Next, a cover tape is attached to a part of the protective film 110 so as to cover the external connection terminal portion of the lower electrode 103 and the external connection terminal portion of the upper electrode 105. The cover tape is made of resin and can be easily detached from the protective film 110. The cover tape prevents dust from adhering to the external connection terminal portion of the lower electrode 103 and the external connection terminal portion of the upper electrode 105.

  Next, the silicon wafer is divided to form a plurality of inkjet heads 21. The inkjet head 21 is mounted inside the inkjet printer 1. A control unit is connected to the external connection terminal portion of the lower electrode 103 and the external connection terminal portion of the upper electrode via, for example, a flexible cable.

  Next, the ink flow path structure 400 is bonded to the back surface of the pressure chamber structure 120. That is, the ink flow path structure 400 is bonded with an epoxy adhesive. Furthermore, the ink supply port and the ink discharge port of the ink flow path structure 400 are connected to an ink tank (not shown) via a tube, for example.

  As described above, in this embodiment, the nozzle plate 100 is formed on the pressure chamber structure 120. However, instead of creating the nozzle plate 100 on the pressure chamber structure 120, a part of the pressure chamber structure 120 may be the diaphragm 101. For example, the driving element 113 is formed on one surface of the pressure chamber structure 120, and a hole corresponding to the pressure chamber 121 is formed from the other surface side. The hole does not penetrate the pressure chamber structure 120. A thin layer remains on one surface side of the pressure chamber structure 120, and this portion operates as the vibration plate 101.

  According to the inkjet head 21 of the first embodiment, the contact hole 107 of the inter-wiring insulating film 106 is formed at a position away from the region where the pressure chamber 121 of the pressure chamber structure 120 exists. Thereby, the connection part of the upper electrode 105 and the extraction electrode 108 can be arrange | positioned in the solid part of the pressure chamber structure 120 which is a highly rigid part in which the pressure chamber 121 is not formed. Here, since the solid portion of the pressure chamber structure 120 that constitutes the peripheral wall portion of the pressure chamber 121 is a region that is hardly displaced when the drive element 113 is driven, for example, a connection portion between the upper electrode 105 and the extraction electrode 108 Is provided in a region facing the solid portion of the pressure chamber structure 120 with the drive element 113 interposed therebetween, so that repeated stress that causes a decrease in reliability can be reduced. Therefore, it is possible to make it difficult for the repeated stress when driving each driving element 113 to drive each driving element 113 to be applied to the connection portion between the upper electrode 105 and the extraction electrode 108. Therefore, it is possible to suppress cracks generated at the connection portion between the upper electrode 105 and the extraction electrode 108, suppress dielectric breakdown from the crack, and further suppress contact failure at the connection portion between the upper electrode 105 and the extraction electrode 108. . As a result, long-term reliability of the inkjet head 21 can be ensured.

  Next, a second embodiment will be described with reference to FIG. In the ink jet head 21 of the second embodiment, the drive element 113 is disposed on the first surface (upper surface in FIG. 8) 120b on the surface side of the plate material of the pressure chamber structure 120, and the plate material of the pressure chamber structure 120 The nozzle 109 is arranged on the second surface (the lower surface in FIG. 8) 120c on the back surface side. Furthermore, the contact hole 107 connecting the upper electrode 105 and the extraction electrode 108 provided in the driving element 113 is a high hole in which the pressure chamber 121 in the plate member of the pressure chamber structure 120 is not formed, as in the first embodiment. The pressure chamber structure 120 which is a rigid portion is disposed in a solid portion.

  Thereby, the connection part of the upper electrode 105 and the extraction electrode 108 can be arrange | positioned in the solid part of the pressure chamber structure 120 which is a highly rigid part in which the pressure chamber 121 of the board | plate material of the pressure chamber structure 120 is not formed. Therefore, in this embodiment as well, as in the first embodiment, the connection portion between the upper electrode 105 and the extraction electrode 108 is provided in a region facing the solid portion of the pressure chamber structure 120 with the drive element 113 interposed therebetween. The connection portion between the upper electrode 105 and the extraction electrode 108 has a structure in which repeated stress is not easily applied. Therefore, it is possible to suppress cracks generated at the connection portion between the upper electrode 105 and the extraction electrode 108, suppress dielectric breakdown from the crack, and further suppress contact failure at the connection portion between the upper electrode 105 and the extraction electrode 108. . As a result, long-term reliability of the inkjet head 21 can be ensured.

  According to these embodiments, it is possible to provide an ink jet head, an ink jet recording apparatus, and a method for manufacturing the ink jet head that can suppress cracks due to repeated stress of the drive element and can improve the reliability of each drive element. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

    DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 10 ... Housing | casing, 11 ... Paper feed cassette, 12 ... Paper discharge tray, 13 ... Holding roller, 14 ... Conveying device, 15 ... Holding device, 16 ... Image forming device, 17 ... Static elimination peeling device, 18 DESCRIPTION OF SYMBOLS ... Reverse device, 19 ... Cleaning device, 19a ... Cleaning member, 21 ... Inkjet head, 100 ... Nozzle plate, 101 ... Vibration plate, 101a ... First surface, 101b ... Second surface, 102 ... Insulating film on substrate, 102a ... first surface, 102b ... second surface, 103 ... lower electrode, 103a ... electrode portion, 103b ... extension portion, 104 ... piezoelectric film, 105 ... upper electrode, 105a ... electrode portion, 105b ... extension portion, 106 ... Inter-wiring insulating film, 106a ... Part without the inter-wiring insulating film 106, 107 ... Contact hole, 108 ... Lead electrode, 109 ... Nozzle, 110 ... Protective film, DESCRIPTION OF SYMBOLS 11 ... Ink repellent film, 113 ... Drive element, 120 ... Pressure chamber structure, 120a ... SiO2 film, 120b ... 1st surface, 120c ... 2nd surface, 121 ... Pressure chamber, 400 ... Ink channel structure 401: Ink flow path.

Claims (5)

A substrate having a pressure chamber for containing ink;
A diaphragm having a first surface that closes the pressure chamber, and a second surface opposite to the first surface;
A driving element that is on the second surface of the vibration plate, changes the volume of the pressure chamber by deforming the vibration plate when a voltage is applied, and discharges ink from the nozzle;
The drive element is
A first electrode on the second surface of the diaphragm;
A second electrode facing the first electrode;
A piezoelectric body interposed between the first electrode and the second electrode,
An inter-wiring insulating film covering the second surface of the diaphragm and the drive element;
And further comprising an extraction electrode on the inter-wiring insulating film,
The inter-wiring insulating film has a contact portion that exposes a part of the second electrode and connects the second electrode and the extraction electrode;
The ink jet head according to claim 1, wherein the contact portion is disposed at a position corresponding to a solid portion of the peripheral wall of the pressure chamber in the base material. The drive element is formed inside the outer periphery of the peripheral wall of the pressure chamber,
The second electrode has an extending portion that extends outward from the outer periphery of the peripheral wall of the pressure chamber,
The inkjet head according to claim 1, wherein the contact portion is disposed at a position corresponding to the extending portion of the second electrode. The base material has the pressure chamber formed by a through-hole,
The solid portion is formed by a peripheral wall portion of the pressure chamber,
The inkjet head according to claim 2, wherein the extending portion of the second electrode is formed in the solid portion. The drive element is disposed on the first surface on the surface side of the plate material of the base material,
The nozzle is disposed on the second surface of the back surface of the base material plate,
The contact portion that connects the second electrode and the extraction electrode provided in the driving element is disposed at a position corresponding to a solid portion of the peripheral wall of the pressure chamber in the base material. Item 10. The inkjet head according to Item 1.   An ink jet recording apparatus comprising the ink jet head according to claim 1.